Water hardness, especially as calcium, is an important parameter along with pH and alkalinity in maintaining the water chemistry of a swimming pool or hot tub. Water hardness includes both calcium and magnesium ions that are found naturally in water and will vary in concentration based on region and water source. Water sources include lakes, rivers, streams, and groundwater (wells) with groundwater typically being the highest since minerals are picked up by rainwater as it percolates through the soil. For examples in areas with a lot of limestone the groundwater will be high in calcium carbonate.
Hardness is an important measurement since if the levels are high the calcium carbonate is likely to precipitate, especially as the pH increases, will lead to cloudy water, clogged filters, and heater inefficiency. If hardness is low then the pool water will attack with calcium carbonate (lime) that is used in grout and concrete leading to pitting and etching.
The HI38904 is a titration-based chemical test kit that determines the total hardness concentration within the 0 to 800 ppm (mg/L) range. The HI38904 is supplied with all of the necessary reagents and equipment to perform the analysis for total hardness.
- Complete setup
- All required materials are included with the test kit, such as the sample beaker and reagent dropper bottle.
- High resolution
- Readings from 0 to 800 ppm (mg/L) are determined with a 10 ppm (mg/L) resolution.
Hardness Level |
℉H |
°dH |
ppm (mg/L) |
Very Soft |
0 – 7 |
0 – 4 |
0 – 70 |
Soft |
7 – 15 |
4 – 8 |
70 – 150 |
Slightly Hard |
15 – 25 |
8 – 14 |
150 – 250 |
Medium Hard |
25-32 |
14 – 18 |
250 – 320 |
Hard |
32 – 42 |
18 – 23 |
320 – 420 |
Very Hard |
>42 |
>23 |
>420 |
1 TH = 1 ℉H = 0.562 °dH = 0.2 meq/L = 10 ppm (mg/L) CaCO3
Ordering info
HI38904 Hardness Chemical Test Kit is supplied with 30 mL hardness buffer, 10 mL calmagite indicator, and 50 mL plastic beaker with cap.
Purchase & Shipping
All prices are inclusive of GST and not all items are stock items, if you require an immediate solution please send an email to sales@hannainst.com.au or call us on (03) 9769 0666.
Free standard delivery: We offer free delivery within Australia on orders over $150, typically arriving within 5 to 7 days. Delivery times may vary depending on the courier service and the recipient's location. Free shipping is not available with other offers or discounts.
Same-day despatch: Place your order before 1 PM Monday to Friday for same-day despatch (leaves our warehouse). Delivery times may vary depending on the courier service and the recipient's location. Subject to stock availability.
Please note that we do not offer shipping to PO Box addresses.